The proposed project has as its long-term goals the understanding and unification of the complex immunological events which may ensue when virus-transformed cells are transplanted into an intact animal. The first phase of this program is concerned with the immunochemical isolation of the tumor specific antigens from hamster tumors or hamster cells transformed by SV-40 virus, and of the antibodies against each antigen. New immunospecific purification methods will be applied which involve the use of chaotropic ions, e.g., perchlorate or thiocyanate, for the elution at neutral pH of antigens (or antibodies) from immunoadsorbents. Chaotropic ions, in combination with more conventional methods, will be used also for the initial solubilization of antigens from tumor cells. The antigens will be isolated from SV-40 induced tumors in hamsters or from SV-40 transformed cells. The antibodies to these antigens will be isolated from immune serum. The possibility of releasing cell-bound antibodies from lymphocytes of SV-40 tumor bearing hamsters will also be explored. The immunological integrity of the resulting purified antigens and antibodies will be tested by immunochemical methods. Availability of these purified materials should make it possible to experimentally manipulate the immunological homeostasis of tumor bearing animals and to determine to what extent immunological factors can control the growth or rejection of primary or transplanted tumors. This long-term goal will be approached by injecting, into tumor bearing animals, the purified tumor specific antigens or their antibodies with or without other agents which may modify immune processes such as complement components, complement inhibitors, anti-lymphocyte antibodies or chemical immunosuppressants, and observing the resulting effects on tumor growth phenomena.